Lathe dog



May 27, 1947.

C. SHALL LATHE DOG Filed March 24, 1944 v INVENTOR. Cam 70M 5 l/flw 4..

Pate'nted May 27, 1947 UNITED STATES PATENT OFFICE 2,421,200 LATHE DocClinton 5. Hall, Farmin ton, Mich.

Application March 24, 1944, Serial No. 527,969

of the invention is to restore the balance.

This object is accomplished generally by means of a counterweightcarried by the bar more remote from the lever. Moreover, the latter baris reversible and is formed with a work-engaging seat in the surfaceopposite the weight as well as in the free end of the weight itself. Theseats are of unequal size corresponding with seats in opposite surfacesof the other bar. Thus, the reversibility of the bars to present unequalpairs of seats for large or small work is not impaired by the presenceof the counter-weight.

Another object of the invention resides in the provision of a retaineror clip to receive the clamping lever and thus hold it from swinginglaterally and loosening the dog. Still another object is to provide inone of the barsa seat for the nut mounted on the bolt that carries thelever. Thus this bolt can beadjusted by turning the lever, since the nutis held in its seat. By the provision of a pressure .cam on each side ofthe lever at its pivoted end, a half-turn adjustment of the bolt becomespossible.

The invention is fullydisclosed by wayof example in the iollowingdescription and in the accompanying drawing in which Figure 1 is anelevation ofthe face plate of a lathe and of the dog secured on thework;

Figure '2 is an elevation of -a modified form of lathe dog;

Figure 3 is an elevation of a modified dog in a different adjustmentwith a modified form of lever retaining clip.

Figure 4 is an elevation of still another modification;

Figure 5 is a section on the line 5-5 of Figure 1 and,

Figure 6 is a section on the line 6-6 of Figure 3.

Reference to these views will now be made by use of like characterswhich are employed to designate corresponding parts throughout.

In Figure 1 is shown the face plate I of a lathe, adjacent to which iscentered the work W on a center (not shown) in a manner well known inthe art as shown in my co-pending application.

3 Claims. (Cl. 82-41) -V seat I3 of a larger size.

and driving the work through lathe dog, as will presently be shown.

The lathe dog includes a pair of bars 3 and 1! joined at their ends bytwo bolts 5 and 6 passed slidably therethrough. The bolt 5 has its upperend flattened at 1 above the upper bar 3 and has a locking lever 8pivotally attached thereto. The other end of the lever is received in aU-shaped clip 0 suitably attached to the upper end of the bolt 6 by aswivel connection, by welding, or by other suitable means. The lowerends of the bolts are retained by nuts 10, and the bolts are normallyspread by coil springs H thereon between the bars 3, 4. The clip mayhave a restricted neck 9 as shown in Figure 5.

One surface of each bar is formed with a V seat 92 adapted to engage theWork W. The opposite surface of each bar is formed with a These seatsare adapted to engage work of larger diameter and are brought inward byremoving the nuts l0 and reversing the bars.

The pivoted end of the lever B has a cam 14 formed oneach side of thepivoted axis. Either cam tightens the bars against the work on swingingthe lever into the clip 9, after preliminary adjustment of the springs ll. The double cam-arrangement has several advantages. The life is doublethat of a single cam, or the wear is reduced-to half. In the raised orvertical position the lever is engaged'by the bar 3 under the pressureof the nearer spring H and therefore will not drop to either side, sothat the dog remains loose until positively tightened by swinging thelever *byhand. Finally, in tightening or loosening one of the springs Hby turning the bolt 5 at the lever, a half turn adjustment can be made,since a cam M is available on either side of the lever. The pin 2engages the free end of the lowered lever, and the clip 9 prevents thelever from swinging laterally.

In the modification shown in Figure 2, one of the bars I5 has seats 16and I! of different sizes on opposite surfaces. The other bar I8 has ariser [9 at the center of one surface, with a seat 2!! formed thereincorresponding to the seat ll. The other surface of the bar I8 has a seat2| corresponding tothe seat IS.

The bars are joined by bolts 23 and 24 surrounded by springs 25 betweenthe bars. A lever 26 is pivotally attached to the bar 23 and received ina clip 21 on the bar 24, as previously set forth.

For small work the riser I9 is positioned inward and the smaller seatsl1 and 20 are enare reversed, bringing the riser l9 outward, as inFigure 3, and presenting the larger seats to the the work.

The size of the riser is such that the weight of the assembly is equallydivided on opposite sides of a plane passed between the bars and throughthe center of the work. In other words, the riser portion isapproximately equal in weight to the lever 26. The dog is therebybalanced about its center of rotation, resulting in balanced momentsduring rotation. This is an important consideration at high speed sincean unbalanced condition would produce excessive wear in the lathe.

The modification shown in Figure 3 difiers principally in the lockingclip for the lever. The dog consists of a pair of bars 30, 31 joined bybolts 32, 33, with a lever 34 pivoted on the bolt 32.

The clip 35 is a simple U-shaped member having a swivel mounting on thebolt 33. The bar 3| has a balancing riser 36 as previously described.

One end of the bar 3| has seats 37 formed in opposite surfaces toreceive the nut 3.8 on the lower end of the bolt 32 in either adjustmentof the bar. With the nut thus held against turning, the entiretensioning of the spring 39 on the bolt 32 can be accomplished byturning the lever 34.

In Figure 4 the upper bar 40 is formed with a notch M for the leverretaining clip 42. The lower bar 43 has a balance riser 44 and is formedwith notches 45, 46 on opposite surfaces and at opposite sides of theriser. Whether the riser is in the inward or outward position, one ofthe notches receives the bolt 41 carrying the lever 48. The nut 49 onthe bolt is of course seated in the downwardly facing notch, and thebolt 4? can be turned to adjust the spring 50 by merely rotating thelever 48. As previously indicated, a half turn adjustment of the boltmay be made by reason of the cams on both sides of the pivoted axis 52of the lever.

The V-notches in the various bars may be serrated, if desired, forbetter gripping. A pin 53 extends from the bar 43 for engagement by thedriving pin of the face plate, as an alternative to driving on theclamping lever.

Although specific embodiments of the invention have been illustrated anddescribed, it will be understood that various alterations in the detailsof construction may be made without departing from the scope of theinvention as indicated by the appended claims.

What I claim is: 7

1. A driver comprising a pair of parallel bars, a pair of bolts passedslidably through the ends thereof, a spring on each bolt between saidbars and adapted to spread the bars, a lever pivoted 4 on an end of oneof said bolts, and a retainer for said lever on the corresponding end ofthe other bolt, said retainer being resilient and having a restrictedneck of less internal width than the entering thickness of said lever.

2. A driver comprising a pair of parallel bars, a pair of bolts passedslidably through the ends thereof, a spring on each bolt between saidbars and adapted to spread the bars, a lever pivoted on an end of one ofsaid bolts, the bar more remote from said lever having work-engagingseats formed in the-center of its opposite surfaces and nut-receivingseats in said surfaces and diagonally disposed relatively to either ofthe workengaging seats, the nut-receiving seats being positioned forpenetration selectively by the threaded end of the bolt carrying saidlever and adapted to receive a nut threaded on the last named bolt,whereby the spring on said bolt may be adjusted by rotating said leveron the axis of said last named bolt.

3. A driver comprising a pair of parallel bars, a pair of bolts passedslidably through the ends thereof, a spring on each bolt between saidbars and adapted to spread the bars, a lever pivoted on an end of one ofsaid bolts, and a counterweight carried by the bar more remote from saidlever and adapted to balance said lever, said counter-weight beingdisposed at the center of the last named bar and having a Work-engagingseat formed in its free end, the opposite surface of said bar. beingalso formed with a work-engaging seat, opposite surfaces of said barbeing formed with nut-receiving seats diagonally disposed relatively toeither of the work-engaging seats, the nut-receiving seats beingpositioned for penetration selectively by the threaded end of the boltcarrying said lever and adapted to receive a nut threaded on the lastnamed bolt, whereby the spring on said bolt may be adjusted by rotatingsaid lever on the axis of said last named bolt.

CLINTON S. HALL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 590,605 Wren Sept. 28, 1897877,882 Blum Jan. 28, 1908 1,012,967 Barter Dec. 26, 1911 FOREIGNPATENTS Number Country Date 20,907 Great Britain Sept. 5, 1896 23,496Germany Dec. 13, 1882 36,845 Switzerland Apr. 3, 1906

